In general, electronic systems are referenced with respect to a ground potential, which can for example be a reference voltage with respect to which the power supply voltages are fixed. This ground may or may not be connected to the earth.
In certain cases, it is necessary for electronic sub-systems or parts to be referenced to potentials other than the ground potential of the overall system, and floating with respect to the latter. This scenario is encountered for example in measuring systems in order to be unaffected by electrical interferences that are sources of noise.
Sometimes, the floating part is not totally separated from the rest of the system by galvanic isolation but is only floating for high frequencies, or about a working frequency.
Special arrangements are necessary in order to be able to provide electrical power to a floating sub-system and to transmit analogue and/or digital signals between that floating system and the part referenced to the ground potential.
This scenario is for example encountered in the document FR 2 756 048 by Rozière which discloses a capacitive measuring system. The detection circuit comprises a high frequency floating part the reference potential of which oscillates with respect to the ground of the overall system at an oscillation frequency.
The power supply voltages are transmitted to the floating part via inductance coils or chokes placed in series in the power lines so as to have a high impedance at the oscillation frequency of the floating reference potential.
The same principle can be used for transmitting digital or analogue signals.
Signals can also be transmitted between the floating and non-floating parts by other known means such as differential amplifiers, photocouplers or radio transmission means.
Electronic functions must often be produced in the form of integrated electronic circuits with minimal overall dimensions and electrical consumption. This is particularly true for capacitive measuring systems which are increasingly used for producing touch sensitive interfaces of portable systems (telephones, computers, etc.).
In this context, the known means for transmitting signals between floating and non-floating parts have inconvenient drawbacks, such as high overall dimensions and consumption.
The purpose of the present invention is to propose a device making it possible to interconnect floating electronic systems with systems referenced to ground, which consume a minimum of energy and which can be produced with small overall dimensions.